Rotary fluid machine

ABSTRACT

A rotary fluid device includes a cylinder having an annular cylinder chamber and an annular piston, which is disposed in the cylinder chamber to be eccentric relative to the cylinder. The annular piston divides the cylinder chamber into an outer working chamber and an inner working chamber. A blade is disposed in the cylinder chamber to partition each of the working chambers into a high-pressure space and a low-pressure space. The cylinder and the piston relatively rotate. The outer working chamber constitutes a compression chamber which compresses and discharges a sucked fluid with the progress of the relative rotation of the cylinder and the piston. The inner working chamber constitutes an expansion chamber which expands and discharges a sucked fluid with the progress of the relative rotation of the cylinder and the piston.

TECHNICAL FIELD

The present invention relates to a rotary fluid device and specificallyto a rotary fluid device having a compression chamber and an expansionchamber.

BACKGROUND ART

Conventionally, there has been a fluid device including a compressionmechanism and an expansion mechanism as disclosed in Patent Document 1.The fluid device has a rotary compressor accommodated in the lower partof the casing and a scrollable expander accommodated in the upper partof the casing. The fluid device also includes an electric motor betweenthe compressor and the expander. The compressor and expander are coupledto both ends of a drive shaft which is connected to the motor.

The compressor compresses a refrigerant. The compressed refrigerantdischarges heat in a heat exchanger and is then expanded by theexpander. The expanded refrigerant absorbs heat in another heatexchanger and returns to the compressor. This cycle is repeated. In theexpander, rotational power generated by the expansion of the refrigerantis recovered. The recovered rotational power and the rotational power ofthe electric motor drive the compressor. As a result, efficient drivingis realized.

[Patent Document 1] Japanese Laid-Open Patent Publication No.2003-138901

DISCLOSURE OF INVENTION Problems to be Solved by the Invention

However, in the conventional fluid device, the compressor and theexpander are placed on different planes. Therefore, the overall size ofthe device is large, and the number of parts is also large.Specifically, the compressor is placed in the lower part of the casingwhile the expander is placed in the upper part of the casing, and thisarrangement increases the overall vertical dimension of the device.Further, the compressor and the expander are completely separate fromeach other so as not to have any common part, and therefore, the overalldevice has a large number of parts.

The present invention was conceived in view of the above problems.Objectives of the present invention are reducing the number of parts anddecreasing the overall dimensions of the device.

Means for Solving the Problems

As shown in FIG. 1, the first invention comprises a rotation mechanism(20). The rotation mechanism (20) includes: a cylinder (21) having anannular cylinder chamber (50); an annular piston (22) which isaccommodated in the cylinder chamber (50) to be eccentric relative tothe cylinder (21), the annular piston (22) dividing the cylinder chamber(50) into an outer working chamber (51) and an inner working chamber(52); and a blade (23) placed in the cylinder chamber (50) andpartitioning each of the working chambers (51, 52) into a high-pressurespace and a low-pressure space, the cylinder (21) and the piston (22)being relatively rotatable. One of the two working chambers (51, 52)constitutes a compression chamber which compresses and discharges asucked fluid with the progress of the relative rotation of the cylinder(21) and the piston (22). The other of the two working chambers (51, 52)constitutes an expansion chamber which expands and discharges a suckedfluid with the progress of the relative rotation of the cylinder (21)and the piston (22).

In the first invention, as the rotation mechanism (20) is driven, thecylinder (21) and the piston (22) relatively rotate, so that the volumeof the compression chamber (51) decreases to compress the fluid, whilethe volume of the expansion chamber (52) increases to expand the fluid.The expansion of the fluid allows recovery of power.

According to the second invention, in the first invention, a suctionmechanism (60) is further provided. The suction mechanism (60) allowsthe refrigerant to be introduced into the expansion chamber (52) in apredetermined rotation angle range of the piston (22) such that anexpansion process of the fluid in the expansion chamber (52) occurs in apredetermined range within one rotation cycle of the piston (22)relative to the cylinder (21).

In the second invention, the fluid is introduced into the expansionchamber (52) by the suction mechanism (60) within a predeterminedrotation angle range of the piston (22). As a result, the expansionprocess of the fluid in the expansion chamber (52) occurs in apredetermined range within one rotation cycle of the piston (22)relative to the cylinder (21), such that the pressure and expansion workof the fluid are recovered.

According to the third invention, in the first invention, thecompression chamber (51) is a working chamber formed outside thecylinder chamber (50), and the expansion chamber (52) is a workingchamber formed inside the cylinder chamber (50).

In the third invention, the compression chamber (51) is formed outsidethe cylinder chamber (50) while the expansion chamber (52) is formedinside the cylinder chamber (50). Therefore, a predetermined compressioncapacity is achieved.

According to the fourth invention, in the first invention, a drivemechanism (30) for driving the rotation mechanism (20) is furtherprovided. The rotation speed of the drive mechanism (30) is variablycontrolled.

In the fourth invention, the rotation of the drive mechanism (30) iscontrolled. Therefore, the operation is carried out according torequired performance such that the efficiency is further improved.

According to the fifth invention, in the first invention, the piston(22) has the shape of C formed by removing a part of its annularstructure to make a slit. The blade (23) extends between an innerperipheral wall surface and an outer peripheral wall surface of thecylinder chamber (50) through the slit of the piston (22). A swing bush(27) is provided in the slit of the piston (22) so as to be in surfacecontact with the piston (22) and the blade (23) such that the blade (23)is reciprocatable and swingable relative to the piston (22).

In the fifth invention, the blade (23) reciprocates in the swing bush(27) while the blade (23) and the swing bush (27) integrally swingrelative to the piston (22). With this structure, the cylinder (21) andthe piston (22) rotate while relatively swinging such that the rotationmechanism (20) performs predetermined compression and expansionoperations.

EFFECTS OF THE INVENTION

According to the present invention, the compression chamber (51) and theexpansion chamber (52) are formed outside and inside the piston (22),respectively. Therefore, the overall size of the device is decreased.

Since the compression chamber (51) and the expansion chamber (52) arelocated adjacent to each other on the same plane, some components can beshared therebetween, resulting in a decrease in the number ofcomponents.

According to the second invention, since introduction of the refrigerantinto the expansion chamber (52) is limited only to a predeterminedrotation angle, even expansion work can also be recovered. Therefore,the efficiency is further improved.

According to the third invention, since the compression chamber (51) isformed outside the cylinder chamber (50) and the expansion chamber (52)is formed inside the cylinder chamber (50), the compression capacity isfully utilized.

According to the fourth invention, since the rotation of the drivemechanism (30) is controlled, the operation efficiency is furtherimproved.

According to the fifth invention, the swing bush (27) is provided as acoupling member for coupling the piston (22) and the blade (23) and isconfigured to be substantially in surface contact with the piston (22)and the blade (23). This arrangement avoids the wearing-away of thepiston (22) and the blade (23) and the burning of the contact portionstherebetween during operation.

Since the swing bush (27) is provided to be in surface contact with thepiston (22) and the blade (23), the contact portions achieves excellentsealing characteristics. Therefore, leakage of a refrigerant from thecompression chamber (51) and the expansion chamber (52) is surelyprevented, and decreases in the compression efficiency and expansionefficiency are also prevented.

Since the blade (23) is integrally provided to the cylinder (21) andsupported at both ends by the cylinder (21), it is less likely to applyan abnormal concentrated load to the blade (23) and cause stressconcentration during operation. Thus, the slidable portion is moreresistant to damage. This feature also improves the reliability of themechanism.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a vertical cross-sectional view of an expansion/compressionunit according to an embodiment of the present invention.

FIG. 2 is a circuit diagram showing a refrigerant circuit which has anexpansion/compression unit.

FIG. 3 is a horizontal cross-sectional view of an expansion/compressionmechanism.

FIG. 4 shows horizontal cross-sectional views which illustrate anoperation of an expansion/compression mechanism.

DESCRIPTION OF REFERENCE NUMERALS

-   -   1 Compressor    -   10 Casing    -   20 Expansion/compression mechanism (rotational mechanism)    -   21 Cylinder    -   22 Piston    -   23 Blade    -   24 External cylinder    -   25 Internal cylinder    -   27 Swing bush    -   30 Electric motor (driving mechanism)    -   33 Drive shaft    -   50 Cylinder chamber    -   51 Compression chamber    -   52 Expansion chamber    -   60 Suction mechanism    -   61 First path    -   62 Second path

BEST MODES FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described indetail with reference to the drawings.

Embodiment 1

Referring to FIG. 1 to FIG. 3, this embodiment is an application of thepresent invention to an expansion/compression unit (1) which is acompressor including an expander. The expansion/compression unit (1) isincluded in a refrigerant circuit (100).

The refrigerant circuit (100) uses, for example, carbon dioxide (C02) asa refrigerant and is configured to perform at least any of a coolingoperation and a heating operation by compressing CO₂ over the criticalpressure. The refrigerant circuit (100) includes, as shown in FIG. 2, anexterior heat exchanger (101) serving as a heat source-side heatexchanger and an interior heat exchanger (102) serving as a use-sideheat exchanger, which are connected to the expansion/compression unit(1). For example, the refrigerant compressed by theexpansion/compression unit (1) discharges heat in the exterior heatexchanger (101) and is then expanded by the expansion/compression unit(1). The expanded refrigerant absorbs heat in the interior heatexchanger (102) and returns to the expansion/compression unit (1). Thiscycle is repeated, whereby indoor air is cooled by the interior heatexchanger (102). The refrigerant circuit (100) further includes a bypasspassage (104) having an expansion mechanism (103), such as an expansionvalve, or the like, such that the mass flow rate of the refrigerant in acompression chamber (51), which will be described later, and the massflow rate of the refrigerant in an expansion chamber (52) are in harmonywith each other. Specifically, part of the refrigerant which hasdischarged heat in the exterior heat exchanger (101) flows through thebypass passage (104), thereby bypassing the expansion/compression unit(1) to flow into the interior heat exchanger (102).

The expansion/compression unit (1) is a completely hermetic rotary fluiddevice wherein an expansion/compression mechanism (20) and an electricmotor (30) are contained in a casing (10).

The casing (10) includes a cylindrical barrel (11), a top end plate (12)fixed to the top end of the barrel (11), and a bottom end plate (13)fixed to the bottom end of the barrel (11). The barrel (11) has asuction pipe (14) and discharge pipe (15) penetrating through the barrel(11). The suction pipe (14) is connected to the interior heat exchanger(102), while the discharge pipe (15) is connected to the exterior heatexchanger (101). The top end plate (12) has an inlet pipe (1 a) and anoutlet pipe (1 b) penetrating through the top end plate (12). The inletpipe (1 a) is connected to the exterior heat exchanger (101), while theoutlet pipe (1 b) is connected to the interior heat exchanger (102).

The expansion/compression mechanism (20) constitutes a rotationalmechanism as shown in FIG. 3 and is configured to carry out compressionand expansion of refrigerant on the same plane at the same time. Theexpansion/compression mechanism (20) is provided between an upperhousing (16) and a lower housing (17) which are fixed to the casing(10). The expansion/compression mechanism (20) includes a cylinder (21)having an annular cylinder chamber (50), an annular piston (22) which iscontained in the cylinder chamber (50) and which divides the cylinderchamber (50) into a compression chamber (51) and an expansion chamber(52), and a blade (23) which divides each of the compression chamber(51) and the expansion chamber (52) into a high pressure space and a lowpressure space as shown in FIG. 3. The piston (22) in the cylinderchamber (50) is configured to make eccentric revolutions relative to thecylinder (21). Specifically, relative eccentric rotation is made betweenthe piston (22) and the cylinder (21). In embodiment 1, the cylinder(21) having the cylinder chamber (50) is movable, while the piston (22)contained in the cylinder chamber (50) is stationary.

The electric motor (30) includes a stator (31) and a rotor (32) toconstitute a driving mechanism. The stator (31) is placed below theexpansion/compression mechanism (20) and fixed to the barrel (11) of thecasing (10). A drive shaft (33) is coupled to the rotor (32) such thatthe drive shaft (33) rotates together with the rotor (32). The driveshaft (33) vertically penetrates through the cylinder chamber (50).

The drive shaft (33) is provided with an oil-supply passage (not shown)extending axially within the drive shaft (33). An oil-supply pump (34)is provided at the lower end of the drive shaft (33). The oil-supplypassage extends upwardly from the oil-supply pump (34). Lubricating oilaccumulated in the bottom of the casing (10) is supplied to slidablepart of the compression mechanism (20) through the oil-supply passage bythe oil-supply pump (34).

Part of the drive shaft (33) which is contained in the cylinder chamber(50) is eccentric part (35). The eccentric part (35) has a largerdiameter than the other parts of the drive shaft (33) above and belowthe eccentric part (35) and is eccentric from the axial center of thedrive shaft (33) by a predetermined amount.

The cylinder (21) includes an outer cylinder (24) and an inner cylinder(25). The outer cylinder (24) and the inner cylinder (25) are integrallycoupled at their lower ends by an end plate (26) to each other. Theinner cylinder (25) is slidably fitted to the eccentric part (35) of thedrive shaft (33).

The piston (22) is formed integrally with the upper housing (16). Theupper housing (16) and the lower housing (17) have bearings (1 c, 1 d)for supporting the drive shaft (33). Thus, the expansion/compressionunit (1) of this embodiment takes on a through-axis structure whereinthe drive shaft (33) vertically penetrates through the cylinder chamber(50) and parts of the drive shaft (33) on both axial sides of theeccentric part (35) are supported by the bearings (1 c, 1 d) in thecasing (10).

The expansion/compression mechanism (20) includes a swing bush (27)through which the piston (22) and the blade (23) are movably coupled toeach other. The piston (22) has the shape of C formed by removing a partof an annular structure to make a slit. The blade (23) extends betweenan inner peripheral wall surface and an outer peripheral wall surface ofthe cylinder chamber (50) through the slit of the piston (22) in aradial direction of the cylinder chamber (50) and is fixed to the outercylinder (24) and the inner cylinder (25). The swing bush (27)constitutes, at the slit of the piston (22), a coupling member forcoupling the piston (22) and the blade (23).

The inner peripheral surface of the outer cylinder (24) and the outerperipheral surface of the inner cylinder (25) represent concentricallydisposed cylindrical surfaces, between which a single cylinder chamber(50) is formed. The outer peripheral surface of the piston (22) has asmaller diameter than the inner peripheral surface of the outer cylinder(24), and the inner peripheral surface of the piston (22) has a largerdiameter than the outer peripheral surface of the inner cylinder (25).Thus, a compression chamber (51) serving as a working chamber is betweenthe outer peripheral surface of the piston (22) and the inner peripheralsurface of the outer cylinder (24), and an expansion chamber (52)serving as a working chamber is between the inner peripheral surface ofthe piston (22) and the outer peripheral surface of the inner cylinder(25).

The piston (22) and the cylinder (21) are configured as follows: whenthe outer peripheral surface of the piston (22) substantially makescontact with the inner peripheral surface of the outer cylinder (24) atone point (strictly, there is a gap on the order of microns but nosignificant leak of a refrigerant from the gap), the inner peripheralsurface of the piston (22) substantially makes contact with the outerperipheral surface of the inner cylinder (25) at one point which isdifferent in phase by 180 degrees from the contact point between theouter peripheral surface of the piston (22) and the inner peripheralsurface of the outer cylinder (24).

The swing bush (27) is formed by a discharge-side bush (2 a) on thedischarge side relative to the blade (23) and a suction-side bush (2 b)on the suction side relative to the blade (23). The discharge-side bush(2 a) and the suction-side bush (2 b) are formed in the same shape toboth have generally semicircular cross sections and disposed to havetheir flat surfaces opposed to each other. The space between the opposedsurfaces of the discharge-side bush (2 a) and suction-side bush (2 b)forms a blade groove (28).

The blade (23) is inserted into the blade groove (28). The flat surfacesof the swing bush (27) are substantially in surface contact with theblade (23), and arc-shaped outer peripheral surfaces of the swing bush(27) are substantially in surface contact with the piston (22). Theswing bush (27) is configured such that the blade (23) reciprocateswithin the blade groove (28) along the surfaces of the blade (23) withthe blade (23) caught in the blade groove (28). The swing bush (27) isalso configured to swing integrally with the blade (23) relative to thepiston (22). In other words, the swing bush (27) is configured such thatthe blade (23) and the piston (22) are swingable relative to each otherwith the central point of the swing bush (27) being the swing center,and the blade (23) is reciprocatable relative to the piston (22) alongthe surfaces of the blade (23).

Although in the example described in this embodiment the discharge-sidebush (2 a) and the suction-side bush (2 b) are independent of eachother, both of the buses (2 a, 2 b) may be partly coupled to each otherso as to form an integral structure.

With the above structure, the rotation of the drive shaft (33) allowsthe outer cylinder (24) and the inner cylinder (25) to swing with thecentral point of the swing bush (27) being the swing center while theblade (23) reciprocates in the blade groove (28). This swing actionallows the contact points between the piston (22) and the cylinder (21)to move sequentially from (A) through (D) in FIG. 4. In this sequence,the outer cylinder (24) and the inner cylinder (25) revolve around thedrive shaft (33) but do not rotate.

Furthermore, the volume of the compression chamber (51) outside thepiston (22) is reduced in the order of (C), (D), (A) and (B) as shown inFIG. 4. The volume of the expansion chamber (52) inside the piston (22)is reduced in the order of (A), (B), (C) and (D) as shown in FIG. 4.

The upper housing (16) has a suction space (41) at a position on theouter periphery of the outer cylinder (24). The suction pipe (14) isconnected to the suction space (41). The outer cylinder (24) has asuction port (42). The suction port (42) allows communication betweenthe compression chamber (51) and the suction space (41). The suctionport (42) is provided in the vicinity of the blade (23), for example, onthe right side of the blade (23) in FIG. 3.

The upper housing (16) has a discharge port (43). The discharge port(43) penetrates the upper housing (16) in its axial direction. The lowerend of the discharge port (43) is open to the high pressure space of thecompression chamber (51). Specifically, the discharge port (43) isformed near the blade (23) and positioned opposite to the suction port(42) relative to the blade (23). The upper end of the discharge port(43) communicates with a discharge space (45) through a discharge valve(44) which is a reed valve for opening/closing the discharge port (43).

The discharge space (45) is provided above the upper housing (16) andunder the lower housing (17). The discharge space (45) provided abovethe upper housing (16) and the discharge space (45) provided under thelower housing (17) communicate with each other through a discharge path(46). The discharge space (45) communicates with the discharge pipe(15).

The inlet pipe (1 a) penetrates through the upper housing (16) to havean opening in the lower surface of the upper housing (16). The openingof the inlet pipe (1 a) faces the upper surface of the inner cylinder(25) and the upper surface of the eccentric part (35) of the drive shaft(33). The opening of the inlet pipe (1 a) is closed by the innercylinder (25) or the eccentric part (35) of the drive shaft (33).

A suction mechanism (60) is formed in the lower surface of the upperhousing (16) and the upper surface of the eccentric part (35) of thedrive shaft (33). The suction mechanism (60) allows the refrigerant tobe introduced into the expansion chamber (52) in a predeterminedrotation angle range of the piston (22) such that a refrigerantexpansion process in the expansion chamber (52) occurs in apredetermined range within one rotation cycle of the piston (22)relative to the cylinder (21). Specifically, the suction mechanism (60)is formed by two paths, a first path (61) and a second path (62).

The first path (61) is formed by a groove having a U-shaped crosssection in the lower surface of the upper housing (16). One end of thefirst path (61) has an opening in the vicinity of the blade (23) on theside closer to the suction port (42). When the piston (22) rotates fromthe bottom dead point (the state shown in FIG. 4(A)), the one end of thefirst path (61) is on an inlet port (4 a) formed in the expansionchamber (52). The first path (61) extends in the axial direction of thedrive shaft (33). The other end has an opening in the vicinity of theinlet pipe (1 a).

The second path (62) is formed by a groove having a U-shaped crosssection in the upper surface of the eccentric part (35) of the driveshaft (33). The second path (62) has the shape of an arc defined aroundthe shaft center of the drive shaft (33) so as to allow communicationbetween the first path (61) and the inlet pipe (1 a) in a predeterminedrotation angle range. Specifically, the second path (62) allowscommunication between the first path (61) and the inlet pipe (1 a)during a period when the piston (22) rotates 90° from the bottom deadpoint (during a period when the state changes from FIG. 4(A) to FIG.4(B)) such that the refrigerant flows into the expansion chamber (52).

The upper housing (16) includes a low-pressure chamber (4 b). Thelow-pressure chamber (4 b) has an outlet port (4 c) and communicateswith the outlet pipe (1 b). The outlet port (4 c) is provided at aposition in the vicinity of the blade (23), which is opposite to the oneend of the first path (61), but on the same side with the discharge port(43), relative to the blade (23), and opens on the expansion chamber(52).

A seal ring (29) is disposed in the lower housing (17). The seal ring(29) is inserted into an annular groove of the lower housing (17) andpressed against the lower surface of the end plate (26) of the cylinder(21). Furthermore, high-pressure lubricating oil is introduced into theinterface (contact surface) between the cylinder (21) and the lowerhousing (17) only radially inside the seal ring (29). In the abovestructure, the seal ring (29) constitutes a compliance mechanism foradjusting the axial location of the cylinder (21), such that axial gapsamong the piston (22), the cylinder (21) and the upper housing (16) arereduced.

The rotation speed of the electric motor (30) is controlled by acontroller (70) having a control circuit, such as an inverter, or thelike.

---Running Operation---

Next, a running operation of the expansion/compression unit (1) isdescribed.

When the electric motor (30) is started, the rotation of the rotor (32)is transferred to the outer cylinder (24) and inner cylinder (25) of theexpansion/compression mechanism (20) via the drive shaft (33). Then, theblade (23) reciprocates (moves forth and back) through the swing bush(27), while the blade (23) and the swing bushing (27) integrally swingrelative to the piston (22). As a result, the outer cylinder (24) andinner cylinder (25) revolve while swinging relative to the piston (22),whereby the expansion/compression mechanism (20) performs predeterminedcompression and expansion operations.

Specifically, when the piston (22) is at the top dead center as shown inFIG. 3(C) and then the drive shaft (33) rotates clockwise, the suctionprocess is started. Subsequently, the structure transitions sequentiallyin the order of (D), (A) and (B) of FIG. 4, so that the volume of thecompression chamber (51) increases and the refrigerant is introducedthrough the suction port (42).

When the piston (22) is at the top dead center as shown in FIG. 4(C),the compression chamber (51) forms a single compression chamber outsidethe piston (22). In this state, the volume of the compression chamber(51) is substantially the maximum. Then, as the drive shaft (33) rotatesclockwise to change the structure in the order of (D), (A) and (B) ofFIG. 4, the volume of the compression chamber (51) decreases so that therefrigerant is compressed. When the pressure in the compression chamber(51) reaches a predetermined value and the pressure difference betweenthe compression chamber (51) and the discharge space (45) reaches a setvalue, the discharge valve (44) is opened by the high-pressurerefrigerant of the compression chamber (51), so that the high-pressurerefrigerant is released from the discharge space (45) through thedischarge pipe (15).

When the piston (22) is at the bottom dead center as shown in FIG. 4(A),the expansion chamber (52) forms a single expansion chamber inside thepiston (22). In this state, the volume of the expansion chamber (52) isthe maximum. Then, as the drive shaft (33) rotates clockwise to changethe structure in the order of (B), (C) and (D) of FIG. 4, the volume ofthe expansion chamber (52) decreases so that low-pressure refrigerant isreleased from the outlet port (4 c) to the outlet pipe (1 b) through thelow-pressure chamber (4 b).

As for the expansion chamber (52), when the piston (22) is at the bottomdead center as shown in FIG. 4(A), communication is established betweenthe first path (61) and the second path (62) while the inlet pipe (1 a)communicates with the second path (62), whereby the suction process isstarted. Thereafter, as the drive shaft (33) rotates clockwise, thefirst path (61) communicates with the expansion chamber (52) so that thehigh-pressure liquid refrigerant flows into the expansion chamber (52).Then, when the drive shaft (33) rotates 90° to form the structure ofFIG. 4(B), the communication between the first path (61) and the secondpath (62) is interrupted. Thereafter, as the drive shaft (33) rotates tochange the structure as shown in FIG. 4(C) and then FIG. 4(D), thevolume of the expansion chamber (52) increases so that the high-pressurerefrigerant expands, whereby the structure is returned to the state ofFIG. 4(A). The pressure and expansion work of the high-pressurerefrigerant are recovered for the rotation of the drive shaft (33).

As described above, the refrigerant is compressed in the compressionchamber (51), and heat is released in the exterior heat exchanger (101).Meanwhile, the high-pressure refrigerant from the exterior heatexchanger (101) expands in the expansion chamber (52), heat is absorbedin the interior heat exchanger (102), and the low-pressure refrigerantreturns to the compression chamber (51).

---Effects of Embodiment---

As described above, according to this embodiment, the compressionchamber (51) and the expansion chamber (52) are formed outside andinside the piston (22), respectively. Therefore, the overall size of thedevice is decreased.

Since the compression chamber (51) and the expansion chamber (52) arelocated adjacent to each other on the same plane, some components can beshared therebetween, resulting in a decrease in the number ofcomponents.

Since introduction of the refrigerant into the expansion chamber (52) islimited only to a predetermined rotation angle, even expansion work canalso be recovered. Therefore, the efficiency is further improved.

Since the compression chamber (51) is formed outside the cylinderchamber (50) and the expansion chamber (52) is formed inside thecylinder chamber (50), the compression capacity is fully utilized.

Since the rotation of the electric motor (30) is controlled by thecontroller (70), the operation efficiency is further improved.

The swing bush (27) is provided as a coupling member for coupling thepiston (22) and the blade (23) and is configured to be substantially insurface contact with the piston (22) and the blade (23). Thisarrangement avoids the wearing-away of the piston (22) and the blade(23) and the burning of the contact portions therebetween duringoperation.

Since the swing bush (27) is provided to be in surface contact with thepiston (22) and the blade (23), the contact portions achieves excellentsealing characteristics. Therefore, leakage of a refrigerant from thecompression chamber (51) and the expansion chamber (52) is surelyprevented, and decreases in the compression efficiency and expansionefficiency are also prevented.

Since the blade (23) is integrally provided to the cylinder (21) andsupported at both ends by the cylinder (21), it is less likely to applyan abnormal concentrated load to the blade (23) and cause stressconcentration during operation. Thus, the slidable portion is moreresistant to damage. This feature also improves the reliability of themechanism.

Other Embodiments

According to the present invention, the above-described embodiment maybe modified to have the following alternative structures.

For example, the cylinder (21) may be fixed while the piston (22) may bemovable.

The cylinder (21) may be integrated by coupling the outer cylinder (24)and the inner cylinder (25) at their upper ends by the end plate (26),and the piston (22) may be formed integrally with the lower housing(17).

The piston (22) may be formed in the form of a complete ring from whichno part is removed, while the blade (23) may be divided into an outerblade (23) and an inner blade (23), such that the outer blade (23)advances from an outer cylinder (21) to make contact with the piston(22), and the inner blade (23) advances from an inner cylinder (21) tomake contact with the piston (22).

The refrigerant circuit (100) may only perform heating operation or maybe switched between cooling and heating operations.

Furthermore, the refrigerant of the refrigerant circuit (100) is notlimited to CO₂.

INDUSTRIAL APPLICABILITY

As described above, the present invention is useful for a rotary fluiddevice having a compression chamber and an expansion chamber andespecially suitable for a rotary fluid device having a compressionchamber and an expansion chamber on the same plane.

1. A rotary fluid device comprising a rotation mechanism including acylinder having an annular cylinder chamber, and an annular pistondisposed in the cylinder chamber to be eccentric relative to thecylinder, the annular piston dividing the cylinder chamber into an outerworking chamber and an inner working chamber; and a blade disposed inthe cylinder chamber to divide each of the inner and outer workingchambers into a high-pressure space and a low-pressure space, thecylinder and the piston being relatively rotatable, wherein one of theinner and outer working chambers being a compression chamber whichcompresses and discharges a sucked fluid with a progression of arelative rotation of the cylinder and the piston, and the other of theinner and outer working chambers being an expansion chamber whichexpands and discharges a sucked fluid with a progression of a relativerotation of the cylinder and the piston.
 2. The rotary fluid device ofclaim 1, further comprising a suction mechanism which allows therefrigerant to be introduced into the expansion chamber in apredetermined rotation angle range of the piston such that an expansionprocess of the fluid in the expansion chamber occurs in a predeterminedrange within one rotation cycle of the piston relative to the cylinder.3. The rotary fluid device of claim 1, wherein the compression chamberis a working chamber formed outside the cylinder chamber, and theexpansion chamber is a working chamber formed inside the cylinderchamber.
 4. The rotary fluid device of claim 1, further comprising adrive mechanism for driving the rotation mechanism, with a rotationspeed of the drive mechanism being variably controlled.
 5. The rotaryfluid device of claim 1, wherein the piston is C-shaped to form a gap,the blade extends between an inner peripheral wall surface and an outerperipheral wall surface of the cylinder chamber through the gap of thepiston, and the gap has a swing bushing therein, the swing bushing beingin contact with the piston and the blade such that the blade isreciprocatable and the blade is swingable relative to the piston.